Mechanism for the transmission of rotary motion



Ap l1e, 1935.

A. BERIA MEGHANISM FOR THE TRANSMISSION oF ROTARY MOTION Filed Jan. 50,1935 2 Sheets-Sheet 1 A. BEmA- April, E6, 1935.

MECHANISM FOR 'PHF2 TRANSMISSION OF'ROTARY MOTION Filed Jan.- so; 1933 2Sheets-Sheet 2 Patented Apr. 16, 1935 PATENT y OFFICE MECHANISM Foa THETRANsMissIoN oF ROTARY MOTION Antonio Beria, Turin, Italy v ApplicationJanuary 30, 1933, Serial No. 654,270 In Italy December 7, 1932 4 Claims.

My invention relates to mechanisms for the transmission of -rotarymotion in which the transmission ratio is variable, and has for itsobject a mechanism in which the transmission ratio, variable in acontinuous manner within certain practically chosen limits, isself-regulating according to the variation vof the resistance coupleapplied to the driven shaft of the mechanism, ,in such manner as tomaintain constant the power transmitted. Thus, if the mechanism transmitpower from a practicallyv constant speed motor with a practicallyconstant power output, it will turn the driven-shaft at a speeddepending on the resistance couple applied to it, and precisely at asmuch higher speed as the couple is less, and vice-versa, in such mannerthat the power absorbed by the driven shaft remains practicallyconstant.

Therefore, the mechanism according to this invention finds, in the firstplace, an important, practical application, what has been already saidbeing taken into consideration, in the changespeed gear of motor cars.It is, however, applicable to other different cases, in general to thedrive of operating machines of any type.

The nature, characteristic features, and scope of the invention will befully understood from the following specification, taken in connectionwith the accompanying drawings, in which:

Fig. 1 is a section through the longitudinal vertical axis of themechanism,

Fig. 2 is a partial. cross'section, on a larger scale;

Fig. 3 is a partial view, in perspective, of the driving shaft, withcertain parts keyed on it;

Fig. 4 is a cross section and partial view of the whole mechanism; j

Fig. 5 is a partial horizontal section, on the line V-V f Fig. 4, with aview of other parts of the mechanism;

Fig. 6 is a section onthe line VI--VI of Fig. 5. Like numerals refer tolike parts throughout the several views. Y

Referring -to Fig. l, the driving shaft I, suitably mounted in bearingsformed by theframe I0, which is substantially of box form and en-`closes the whole mechanism, has keyed to it the parts II, IIaconsisting of a boss and one or two arms (see also Fig. 3) integral withit; in the construction represented in the figures, these members areseven in number. The driving shaft is further provided with a toothedwheel I4, keyed on .to it and, towards the end opposite to that whichtakes the drive, with a bell-shaped part I2 having internal teeth I3.

The/arms II, IIa, IIb of thel above mentioned members are each providedwith a rectangular groove, as IIIJ, I IIla, and IIb the axis of which isat right angles tothe axis of the driving shaft I;. the first member II(beginning, for example, from the left) has only one arm, whilst theintermediate ones have two, arranged with their. axes at a certain angleto each other, which in the case shown (see Figs. 2 and 3) is of 120,and the last has, like the rst only one arm. These members are keyed tothe driving shaft at such angles that, for example, one arm of thesecond member (IIa in Fig. 3) is set with its central axis in the sameplane passing through the axis of the shaft I as the central axis of thefirst arm (I I, Fig. 3) and more precisely the central axis of theirrespective grooves are in the same axial plane of I; the other arm ofthe second member is arranged with its central axis inthe same axialplane of I as is the first arm of the third member, andthe second arm ofthis is in the same axial plane as the rst arm of the fourth member II;and so on up to the last member. There is thus arranged around the shaftI a certain number of pairs (six, in the case illustrated) of armsplaced two and two in the same axial plane, and in which the previouslymentioned grooves IIIJ have their respective cavities facing each otheras is, for instance, shown in Fig. 3.for the first pair of arms. In eachpair of grooves, which form together a prismatic guide, or runway, isfitted so as to slide a member which will be described later. The axialplanes of the said pairs of arms divide amongst them the entirecircumference into equal angles, for instance, in the case illustrated,into six angles of Parallel to shaft I and suitably supported in theframe II'I is a secondary shaft 3, on which are loosely mounted thetoothed wheels 39, and 5, which can, however, at will, be locked solidwith the shaft by mean's of two dog clutches, shown schematically at 31and 36 respectively and which are actuated by the rod 38 passing throughan axial cavity in the shaft 3. A third toothed wheel 6l is alsomounted, fast, onthe shaft 3. This shaft further carries two supports oflarge diameter, in the form of` collars, 32 and 33, made fast to eachother by means of a long sleeve 3| rotatably mounted on the shaft 3, andforming one piece with the extensions 34 and 35 with which the supportsare respectively provided; the two supports are coaxial and their axisis parallel to that of the shaft 3, and is as distant from this as theaxis of the shaft I, so that, the assembly of the two supports 32, 33being free to turn about 3, the axis ofthe said supports can be broughtto coincide with that of the shaft I.

In the supports 32, 33 is mounted so that it can revolve a part havingthe form of a cylindrical ldrum 2, provided withheads 2I and 22 ofannular shape and which embraces the shaft I with which it can bebrought coaxial, for a given position of the supports. The drum 2carries as many members 23-24, each formedesubstantial- 1y oftwo coaxialrings, as there are pairs of arms carried by the shaft I, each of saidmembers being located between the two arms of one ofthe said pairs. Eachone of these members is made up of an outer ring, ,23, fast to the drum2 and an inner ring 24, coaxial with and free to turn with respect tothe former by means of any known means of mounting, such as, forinstance, a mounting on ball bearing, which is connected to the formerby a sc-called one-way motion, or free wheel device; that is to say,that Whilst its movement in one direction is free, in the oppositedirection it is engaged in such manner that theA two rings are in thisrespect locked solidly together. This coupling is represented in thedrawings by way of example (Fig. 2), in a conventional manner, as beingconstituted by the interposition between the internal surfaces of therings, the one cylindrical and the other with saw-tooth serrations 21,of cylindrical rollers 26.

Each ring 24 is provided with a revolving pin 25 normal to the plane ofthe ring and provided at its ends with rollers which can run, with asuitable play, respectively in the two grooves, for example Il, IIIla inFig. 2, of the two arms mounted on the shaft I and between which thering is located. The engagement of these end rollers of the pins 25 inthe grooves of the arms II constitutes a connection between the shaft Iand the drum 2; and precisely, when the shaft I turns in the directionin which the rotation of the ring 24 isconnected with that of the ring23, the shaft I will; in turning, carry the drum 2 around with it.

For the sake of simplicity and clearness in the drawings; in Fig. 1 theconnecting members between the shaft I and the drum 2 (II, I Ia, 23, 24,25) are not fully shown except for one of the six elements, that is, thefirst on the left.

When the drum 2 is coaxial with the shaft I, the system of connectionbetween the two members just described is equivalent to a simple freewheelclutch, inasmuch as the shaft, revolvingin the prescribed directionwill carry the drum with it, positively. If, on the contrary, the axisof the drum moves away from that of the shaft, which happens when thesupports 32, 33, with their connecting sleeve 3I, turn about the shaft3, it is obvious that the rotating speed of the different ring elements23, 24, being due to the motion they receive from the arms II throughthe pins 25, is at all times different from element to element, andprecisely according to the distance at which at any time the differentpins 25 are from the axis of rotation of I. Thus, at al1 times, one ofthe inner rings of the aforementioned elements will be revolving at ahigher speed than the others; by virtue of the freewheel connectionbetween the two rings of each element, it will therefore only be thatelement which is turning the fastest that will be transmitting itsmotion to the drum, whilst all the vother outer ringswill be drawnaround by the drum 2 at a higher. speed than that of the correspondinginner rings, that is to say, there will be a relative rotation betweenthe two rings in thev said elements, in the free direction.

When the cylinder 2 is eccentric with the shaft I, it is thereforedriven by the shaft at a speed,

higher than that of the shaft itself, and as much v higher as the degreeof eccentricity is greater. Since each pair of arms II takes up in itsturn the task of driving the drum, there is, for cinematic reasons whichare obvious from the foregoing, at each of these successions (forexample: six times in each revolution, in the case illustrated of amechanism having six elements) a slight pulsation in the speed of thedrum; this pulsation, although small, is, however, eliminated lby theapparatus, as it will be seen further on.

'Ihe drum 2 is provided with a toothed crown 4, by means of which v ittransmits its motion to the toothed wheel 5 mounted on the secondaryshaft 3 and, when the clutch 36 is engaged, to

the shaft itself. The meshing of the toothed wheels 4 and 5 remainsevidently invariable, whatever may be the position the drum 2 assumes inoscillating about 3. It is thus possible lto have on the shaft 3 a speedwhich,for a constant speed of the driving shaft I, varies in acontinuous manner, according to the eccentricity of the` drum 2;nevertheless, V-owing to constructional necessities, the range of suchvariations is comprised within rather narrow limits, which would greatlyreduce the field of application of the mechanism in practice.

In order to be able to obtain variable speeds over a very wide range,and such as to satisfy any practical requirement Whatever, the inventionprovides for the combination of the changeable speed device justdescribed with a differential device which is described hereafter.

A driven shaft 9 is arranged with its axis on the extension of thedriving shaft I and suitably supported by the frame I9; on the end ofthis .shaft is keyed a toothed pinion 9I, the central plane of whichcoincides with that of the toothed crown I3 already mentioned. Coaxiallywith the shaft 9 is mounted, revolving, for example, on ball bearings, amember 8, carrying, rotatably mounted on suitable pins, a certain numberof pinions 8l arrangedsymmetrically around the pinion 9I and in meshwith it and with the toothed crown I3. 'I'he assembly of gear wheels I3,9I and BI forms a differential gear in which I3 is the active member, 9|the passive member and 8| are the planet pinions; whilst the part 8 isthe planet carrier. The latter is fitted with a toothed crown 'I whichengages with the toothed wheel 6, already mentioned, keyed on thesecondary shaft 3.

lThe transmission of the motion from the driving shaft to the drivenshaft therefore takes place through the differential gearing ljustdescribed, the active member of which revolves at the speed, supposedconstant, of the driving shaft, whilst the train of planet pinionsrevolves at a speed which varies according to the eccentricity of thedrum2 with respect to the driving shaft. If the transmission ratios ofthe toothed wheels 4, 5,'6, I and I3, 9| are suitably calculated it willbe possible to obtain, with a limited variation of the ratio oftransmission between the shaft I and the drum 2 (as already mentioned) avery' Wide range of variation of the ratio of transmission between thedriving shaft I and the .driven shaft 9.

The automatic regulation of the ratio of transmission, according to thevariation in the resistance couple applied to the driven shaft, so as tomaintain constant the power transmitted, is obtained in the followingmanner.

It must be noted that the force which is transmitted through the pair oftoothedwheels 4, 5 creates a certain moment about the axis of the shaft3; by reaction therefore the drum 2 will be subjected to the saidmoment, which will tend to make it revolve about the said axis.

In order to balance this moment, and main- .tainthe drum 2 in a definiteposition, in contrast to the reaction which the wheel 5 exerts on wheel4 and which would tend to draw the drum around in the direction of theformer, the drum is anchored (Figs. 4` and 5) by two small connectingrods'5l and 52 forming part of a system of levers on which acts asuitable spring. The connecting rods 5|, 52 are in fact pivoted on theends of a rod 49, parallel to the axis of the drum, mounted, at itscentral point, on the end of a crank 48 keyed on a shaft 4|, parallel torod 49, and pivoted at. its ends on the frame Ill., A helical spring 42,one end of which is fixed to the boss `of the crank 48 and the other tothe part 43, exerts on the system the aforementioned spring action.

Supposing the mechanism tosbeworking under any given speed condition,the force of the spring |232, applied to the drum 2 in the manner justdescribed, will counterbalance the reaction which tends to cause thesaid drum to rotate. If, for any reason whatever, the couple transmittedtends to increase, the reaction moment will also increase; then thespring 42 will give, giving rise to an increase of its elastic power,and allowing Vthe drum 2 to move a certain distance, which will vary thetransmission ratio of the mechanism, and precisely until this ratioreaches that value to which corresponds a reaction moment which will becounterbalanced by Athe new position of the spring.

It is evident that it is possible to calculate the system of levers andthe spring in such a way that the power applied shall not vary with thevariation of the resistance couple. ever, to the presence of thedifferential gear, by virtue of which the power transmitted by themechanism is subdivided between the toothed wheel i3 (Fig. 1) drivendirectly by the driving shaft and the planet carrier 8 driven throughthe speed changing device, by a certain law dependent upon theinstantaneous ratio of transmission, calculations show that the momentto be counterbalanced admits of rather small variations.

The arrangement of the connecting rods 5|, 52 and of the crank 48, whichtransmit to the spring the effects of the displacement of the drum 2,has as its aim the 'suitable' multiplication of the said variations; thefact that during the rotation of the crank 48 the angle it forms withthe connecting rods varies, and therefore `the moment of the effortapplied to the connecting rods with respect to the shaft 4| also varies,further allows a certain law of variation to be obtained, convenientlyassuming the value of the angle mentioned for an intial position of themobile system.V For the determination of such angle, the effectivelength of the connecting rods 5|, 5 2 can be adjusted, as it is shown inthe figure,

by means of the screws 53; this allows of settingI the mechanismwith'absolute exactness.

The initialtension of the spring 42` can, in its turn, be regulated byturning the part 43 in which Owing, howi pne of its ends is fixed, andthis by means of a suitable worm drive as shown in the figure.

Practically, it is possible, with the described I devices to arrangethat whilst the maximum variations of the moment tending to turn thedrum 2 are, for example, 10%, the corresponding variations of the momentabout the shaft 4|, which the spring hasto counteract, are 30%.

It has vbeen said before that', the apparatus according to thisinvention eliminates those pulsations in speed which necessarily arisefrom the adoption of the type of continuous speed changing device abovedescribed. In fact it issuiiicient to observe that for a given powertrans mitted every variation in speed entails a variation in the couple,in order to be convinced that the self-regulating 'mechanism will varythe transmission ratio in such a manner that the said couple will notvary, or in other words, that the speed of the driven member remainsconstant.

The shaft 4| is provided with a device for ,Y

damping out the oscillations of its rotating movement, with the aim ofretarding the said .movement and therefore the oscillations in thetransmission ratio which would otherwise be due to variations even onlymomentary in the resistance couple. p

Such a case arises, for instance, in the application of the mechanismaccording to the invention as a. change speed gear for automobiles,when, through the effect of a bump, the driving wheels leave the roadfor an instant. The resistance couple then falls almost completely tozero, to regain almost at once its primitive value. It is advisable thatthe change speed gear should not act through variations of theresistance couple of such brief duration.

The damping device (Figs. 5 and 6) consists of asegment 44 keyed ononeend of the shaft 4| and revolving in a cylindrical casing 45 fixed tothe frame. One part of the segment, forming its hub, is hermeticallytted against a xed partition 46 of the casing, provided with atransverse hole.46, whilstv the outer end and sides of the segment aretight against the internal cylindrical surface and against the bases ofthe casing. In this manner, if the casing is lled with a suitable fluid,for example, glycerine, the rotation of the segment (and therefore alsoof the shaft 4|) cannot take place withoutxthefluid being obliged topass through the hole 46'., a screw 41 allows of obstructing more orlessthe passage of the .uid, in suchA a manner as to regulate according tothe need, the damping action of the device.

The damping device-can be prevented from diminishing that selfregulating action of the apparatuswhich, asl mentioned shortly before,serves to eliminate the pulsations of speed due to the fundamentalworking itself of the apparatus, acting so that the oscillations of thedrum 2 of an amplitude below a certain limit shall not be transmitted tothe damping device; this may be effected, forinstance, by simf plyintroducing in the connecting members between the said mechanisms, acoupling having a certain liberty of movement (play) The transmissionmechanism according to the invention comprises also a reversing device,particularly opportune in its application to automobiles. For thispurpose the pair of toothed wheels I4, 39 already mentioned isvprovided. When, through the operation of the dog clutches 38, 31 thewheel 5 is made to run loose and wheel 39 is made fast to the shaft 3,the change speed gear of which the drum 2 forms part, revolves loose,whilst the motion is transmitted to the driven shaft, at a constantspeed ratio, still through the differential device, from one sidedirectly from the driving shaft (through the gear wheel I3) and from theother side also from the driving shaft, but through the gears Il, I9 andI, .1. Having chosen suitable transmission ratios for these gears, thespeed of the planet carrier will be such as to produce the rotation ofthe driven shaft in a direction contrary to the normal.

The whole mechanism can Abe conveniently made to work in an oil bath,andforfthis purpose suitable retaining devices are provided for in the-casing forming the frame, where the shafts issue.

It will be 'appreciated that the best known embodiment of my inventionhas been illusytrated and described in detail, and that my inventioncontemplates said changes in structural details and features as mayoccur to persons skilled in the art; accordingly the scope of myinvention is not limited to the example thereof disclosed herein but isdefined broadly by the appended claims. I

l. In mechanism for the transmission of rotary motion with acontinuously variable trans- Ymission ratio, the combination of adriving shaft, Va driven shaft, a member rotatable at variable speedabout an axis parallel to'the axis of rotation of the driving shaft anddriven shafts, means for moving said member bodily about an axisparallel to its axis of rotation to displace the same relatively to thedriving and driven shafts, arms keyed to the driving shaftand extendingradially therefrom and having adjustable driving connections to saidvariable speed member to transmit the rotary motion of the driving shaftto said membenja drive between said bodily .movable member, the drivenshaft thereby to drive the driven shaftat a variable speed, and meansresisting displacement of the rotary member out of its adjusted positionduring the transmission of power from the driving shaft to the drivenshaft.

2. In a'mechanism for the transmission of rotary motion with-acontinuously variable transmission ratio, the combination of a drivingshaft,

l a driven shaft, a drum 'surrounding the driving shaft and rotatable atvariable speed about an axis parallel to the axis of rotation of thedriving shaft and the driven shaft, means for moving said drum bodilyabout an axis parallel to its axis of rotation to displace the samerelativelly to the driving and driven shafts, means envariable speed,and means resisting displacement of the drum out of its adjustedposition during the ton of power from the driving shaft to the drivenshaft.

3. In a mechanism for the transmission of rotary motion with acontinuously variable transmission ratio, the combination of 9, drivingshaft, a driven shaft, a drum surrounding the driving shaft androtatable at variable speed about an axis parallel to the axis ofrotation of the driving shaft and driven shaft, means for moving saiddrum bodily about an axis parallel to its axis of rotation to displacethe same relatively to the driving and driven shafts, arms secured tosaid driving shaft, surrounded by said drum and having drivingconnections to said drum, said connections being varied as the drum isgiven said bodily movement, a secondary shaft, means for transmittingpower from the driving shaft to said secondary shaft through said drum,to drive said secondary shaft at a speed dependent upon the position ofsaid drum relatively to the driving shaft, land differential gearingintermediate the secondary shaft and the driven shaft, the active gearof which is keyed to the driving shaft and the passive gear to thedriven shaft, the intermediate gears of the differential being driven bysaid secondary shaft.

4. In mechanism for the transmission of rotary motion with acontinuously variable transmission ratio, the combination of a drivingshaft and a driven shaft, a drum rotatable about an axis parallel to theaxis of rotation ofthe driving shaft and the driven shaft, means formoving said drum bodily about an axis parallel to its axis of rotationto displace the same relatively to the driving and driven shafts, aplurality of guiding members keyed to the driving shaft and extendingradially thereof, a plurality of slidable members adapted to slide insaid guiding members, a rotary Adrum surrounding the drivrelatively'tothe driving shaft, a secondary shaft rotatable about an axis parallel tothe driving shaft and the driven shaft, and rotated through said drum,and differential gearing intermediate said secondary shaft and thedriven shaft, whereby rotary motion is transmitted from the drivingshaft to the driven shaft with a variable transmission ratio.

ANTONIO BERIA.

